Plastic cap with ic tag and method of attaching ic tag to the cap

ABSTRACT

[Problem] To provide a plastic cap with an IC tag without interrupting transmission and reception of information to and from the IC tag, reliably inputting product information to the IC tag and reliably outputting product information that is input. 
     [Means for Solution] The plastic cap has an IC tag  10  storing product information provided on the upper surface of a top plate  21.  The top plate  21  is formed by an annular flange  35  and a recessed portion  37,  the recessed portion  37  including a side wall  37   a  continuous to the inner circumferential edge of the annular flange  35  and a bottom  37   b  continuous to the lower end of the side wall  37   a.  The IC tag  10  is attached to the annular flange  35  so as to cover the recessed portion  37.  A gap between the IC tag  10  and the bottom  37   b  is maintained to such a degree that the transmission and reception of signals to and from the IC tag  10  are not interrupted when the back surface of the bottom  37   b  comes in contact with water.

TECHNICAL FIELD

This invention relates to a plastic cap having an IC tag storing productinformation attached to a top plate thereof, and to a method ofattaching the IC tag to the plastic cap.

BACKGROUND ART

Bar codes representing product information such as the date ofproduction, names of the manufacturer and distributor, usable term, etc.have heretofore been widely utilized for a variety of kinds of products.Here, the bar codes are such that the encoded information is read out byusing a reader. Therefore, a surface on where the bar code is printedmust be made flat arousing, however, a problem in that limitation isimposed on the surface where the bar code is printed and on the amountof information that can be encoded especially in the field of packingmaterials such as bottles and caps.

In recent years, therefore, a technology for displaying information hasbeen utilized by making use of an IC tag. The IC tag is also called anRFID (radio-frequency identification) and is a communication terminal ofa very small size of the form of a tag in which an IC chip storingpredetermined information is buried together with an r-f antenna in adielectric material such as a resin or a glass. The IC tag reads theproduct information stored in the IC chip through radio communication. Amemory in the IC chip is capable of storing the data of, for example,several hundreds of bytes, offering an advantage of capability forstoring large amounts of product information. Besides, the IC tag canread the stored information in a non-contacting manner withoutaccompanied by such problems as wear due to contact and, further, offerssuch an advantage in that the IC tag can be worked in a shape to meetthe form of the product and in a small size and in a reduced thickness.

As caps provided with the IC tag, patent documents 1 and 2 are proposingthose having an IC tag buried in a top plate.

Patent document 1: JP-A-2006-62716

Patent document 2: JP-A-2005-321935

DISCLOSURE OF THE INVENTION Problems that the Invention is to Solve

The IC tags can be grouped into those of the type which effect thecommunication relying on the electromagnetic induction and those of thetype which effect the communication relying on the electromagneticwaves. The IC tag of the type of electromagnetic induction has anadvantage in that the communication is little affected by wateraccompanied, however, by a defect in that it occupies a large area. TheIC tag of the type of electromagnetic waves, on the other hand, has adefect in that the communication is subject to be affected by water buthas such an advantage that it occupies a small area. At present,therefore, the IC tag of the type of electromagnetic waves has beenstudied in the field of caps.

When the above-mentioned cap having the electromagnetic wave type IC tagprovided in the top plate was applied to a container filled with acontent containing water such as a beverage, however, there remainedsuch a problem that transmission and reception of information becamedifficult. There was no particular problem when, for example, the IC tagwas attached to an upper lid of a cap of the two-piece type comprising acap body fitted to the mouth portion of the container and an upper lidfitted to the cap body. When the IC tag was attached to the uppersurface of a top plate of a cap of the one-piece type which comprisesthe top plate and a skirt wall hanging down from the circumferentialedge portion of the top plate and which is directly fitted to the mouthportion of the container, however, there remained a problem in thatwater contained in a beverage caused dielectric loss or mismatching ofimpedance resulting in the interruption of transmission and reception ofinformation to and from the IC tag.

Further, the IC tag can be attached to the cap by, for example, buryingthe IC tag in the top plate of the cap by insert-molding or byheat-melt-adhering (heat-sealing) the IC tag to the top plate of thecap. In either method, however, the IC tag to be attached to the cap isvery light in weight (usually, about 0.02 g) and is of the shape of asmall piece, which is very difficult to handle. Therefore, it isdifficult to fix the IC tag to a predetermined position in the metalmold at the time of insert-molding or to fix the IC tag to apredetermined position of the top plate at the time of heat-sealing.Namely, the position tends to be easily deviated and, besides, the ICtag tends to fly off in a step of conveying the IC tag to a step offixing the IC tag to the predetermined position, causing theproductivity to become very low.

It is, therefore, an object of the present invention to provide aplastic cap with an IC tag, which enables product information to bereliably input to the IC tag and the product information that is inputto be reliably output without interrupting transmission and reception ofinformation to and from the IC tag.

Another object of the present invention is to provide a method ofattaching an IC tag to a cap, which is capable of effectively avoidingdeviation in position or flying-off of the IC tag that stores productinformation, and of efficiently attaching and fixing the IC tag to thecap.

Means for Solving the Problems

According to the present invention, there is provided a one-pieceplastic cap to be fitted to a mouth of a container which contains awater-containing content, and having a top plate and a skirt wallhanging down from a circumferential edge portion of the top plate and,further, having an IC tag storing product information attached to anupper surface of said top plate, wherein:

-   -   said top plate forms a shielding member that maintains a gap        between the water-containing content in the container and said        IC tag to such a degree that the transmission and reception of        signals to and from the IC tag are not interrupted by the        water-containing content.

In the plastic cap of the present invention, it is desired that:

(1) The top plate is formed by an annular flange and a recessed portioncontinuous to the inner circumferential edge of the annular flange; therecessed portion includes a side wall continuous to the innercircumferential edge of the annular flange, and a bottom continuous tothe lower end of the side wall and the bottom is working as theshielding member; and the IC tag is attached to the annular flange tocover the recessed portion, and wherein a gap between the IC tag and thebottom of the recessed portion is maintained to such a degree that thetransmission and reception of signals to and from the IC tag are notinterrupted when the back surface of the bottom comes in contact withthe water-containing content;(2) The IC tag is attached by heat-melt-adhering the circumferentialedge portion thereof onto the upper surface of the top plate;(3) A protuberance extending upward is formed on the upper surface ofthe bottom of the recessed portion; and(4) The side wall of the recessed portion of the top plate includes anupper large-diameter portion having a relatively large outer diameterand a lower small-diameter portion having a relatively small outerdiameter, an inner ring is formed on the outer circumferential surfaceof the upper large-diameter portion of the side wall so as to extenddownward being separated away from the outer circumferential surface ofthe lower small-diameter portion, and the mouth portion of the containeris inserted in space between the skirt wall and the inner ring so as tobe fixed therein.

According to the present invention, further, there is provided a methodof attaching an IC tag to a plastic cap, comprising steps of:

preparing an IC tag web in which a plurality of IC units of acombination of IC chips and metal antennas are arranged and fixed on onesurface of a first thermoplastic resin substrate sheet, a secondthermoplastic resin substrate sheet, and a plastic cap having a topplate and a skirt wall hanging down from a circumferential edge portionof the top plate;

preparing a laminated sheet in which said IC tag web is laminated on asurface of the second thermoplastic resin substrate sheet byheat-adhering the first thermoplastic resin substrate sheet of said ICtag web and the second thermoplastic resin substrate sheet together in amanner that said IC units are positioned on an outer surface side;

punching said laminated sheet in a disk shape successively for each ofthe IC units fixed thereto to thereby successively form tag pieces ofthe disk shape having the second thermoplastic resin substrate adheredto the IC tag in which one IC unit is fixed to the first thermoplasticresin substrate, and successively fitting and false-fixing the punchedtag pieces onto the upper surfaces of the top plates of the caps in amanner that the second thermoplastic resin substrate is on the outersurface side simultaneously with the punching; and

fixing said IC tag onto the top plate of the cap via the secondthermoplastic resin substrate in an integral form by heat-melt-adheringthe second thermoplastic resin substrate onto the upper surface of thetop plate of the cap.

In the method of attaching the IC tag of the present invention, thefollowing embodiments are preferred: i.e.,

(1) The first thermoplastic resin substrate sheet comprises polyethyleneterephthalate and the second thermoplastic resin substrate sheetcomprises polyolefin;(2) A stepped surface is formed in an annular shape at the outercircumferential edge portion on the upper surface of the top plate ofthe cap, the inner region of the stepped surface forms a surface lowerthan the outer region, and a tag piece punched from the laminated sheetis fitted onto the inner region of the stepped surface;(3) The tag piece punched from the laminated sheet is inserted into aninner portion of the stepped surface in a manner that the outercircumferential end surface of the second thermoplastic resin substrateis closely adhered to the stepped surface, and is, thus, fitted onto, oris fitted and false-fixed onto the upper surface of the top plate of thecap;(4) An undercut is formed in an upper end portion of the stepped surfaceso as to protrude inward, and the tag piece is false-fixed by theengagement of the undercut with an outer circumferential edge portion ofthe second thermoplastic resin substrate;(5) The inner region of the stepped surface on the upper surface of thetop plate of the cap includes an annular flange continuous to the lowerend of the stepped surface and is extending inward, and a recessedportion continuous to the inner circumferential edge of the annularflange, and the tag piece is so fitted that the circumferential edgeportion thereof faces the annular flange;(6) The first thermoplastic resin substrate sheet and the secondthermoplastic resin substrate sheet are heat-adhered together in amanner that at least the IC chip is not pressed on the surface of thefirst thermoplastic resin substrate sheet;(7) The IC tag web is laminated while intermittently feeding the secondthermoplastic resin substrate sheet, the laminated sheet is punchedafter having been laminated, and the punched tag pieces are fitted ontothe top plates of the caps;(8) The second thermoplastic resin substrates possessed by the IC tagpieces are spot-heat-adhered onto the upper surfaces of the top platesof the caps so that the tag pieces are false-fixed while intermittentlyfeeding the caps having the tag pieces fitted onto the upper surfaces ofthe top plates thereof ; and(9) The caps to which the tag pieces are false-fixed are introduced intothe step of continuous feeding, and the second thermoplastic resinsubstrates possessed by the tag pieces are heat-melt-adhered onto theupper surfaces of the top plates of the caps while continuously feedingthe caps so that the IC tags are fixed to the top plates of the capsintegrally therewith.

EFFECTS OF THE INVENTION

In the plastic cap of the present invention, the shielding membermaintains a predetermined gap between the IC tag attached to the annularflange of the top plate and the water-containing content (e.g., variouskinds of beverages like water, juice, etc.) contained in the container.This prevents such an inconvenience that the transmission and receptionare interrupted due to dielectric loss or mismatching of impedancecaused by the water-containing content. It is, therefore, made possibleto reliably transmit (input) the product information to the IC tag andto receive (output) the product information that is input.

The above shielding member can also be attached to the inner surface ofthe top plate. According to the present invention, however, it isdesired to form a recessed portion in the top plate itself so that thebottom of the recessed portion works as the shielding member. By soforming the recessed portion that the bottom thereof works as theshielding member, the cap can be easily molded.

In the present invention, further, upon forming a protuberance on theupper surface of the bottom of recessed portion of top plate of the cap,in case an external force is accidentally exerted from the upperdirection, the IC tag is supported by the protuberance and can,therefore, be effectively avoided from being deformed or damaged. Todiscard the used cap, further, the bottom of the recessed portion ispushed upwards from the back surface thereof, whereby the IC tag iseasily removed from the top plate of the cap offering an advantage fromthe standpoint of disposal in a classified manner.

In the invention, further, the side wall of recessed portion of the topplate can be directly and closely adhered to the inner surface of themouth portion of the container to maintain sealing performance.Desirably, however, an inner ring is provided as a member independentfrom the side wall of the recessed portion, and the mouth portion of thecontainer is inserted into between the inner ring and the skirt wall sothat the inner ring is closely adhered to the inner surface of the mouthportion of the container to maintain sealing performance. That is, tomaintain sealing performance by the side wall of the recessed portion,the mouth portion of the container must be inserted in space between theside wall and the skirt wall. Here, however, since the lower end of theside wall is integral with the bottom, the side wall lacks flexibility.As a result, it may become difficult to insert the mouth portion of thecontainer in space between the side wall and the skirt wall. Besides,adhesion becomes unstable between the side wall and the mouth portion ofthe container, and sealing performance may decrease. Upon providing theinner ring as a member independent from the side wall of the recessedportion, on the other hand, flexibility can be maintained to asufficient degree, which is favorable for avoiding the above-mentionedinconvenience.

The inner ring can be provided at a position, for example, between theskirt wall on the inner surface of annular flange of the top plate andthe side wall of the recessed portion so as to serve as a memberindependent from the side wall of the recessed portion. According to theinvention particularly desirably, further, the inner ring is formed atan intermediate portion of the side wall of the recessed portion.Concretely, it is desired that the side wall of the recessed portion isso formed as to include an upper large-diameter portion located at anupper position and having a relatively large outer diameter and a lowersmall-diameter portion located at a lower position and having arelatively small outer diameter, and the inner ring is so formed as toextend downward from the outer circumferential surface of the upperlarge-diameter portion of the side wall being separated away from theouter circumferential surface of the lower small-diameter portion. Withthe inner ring being provided as described above, space of a suitablesize is maintained between the IC tag and the water-containing contenteven in case the solution in the container infiltrates into spacebetween the inner ring and the side wall of the recessed portion,effectively preventing the transmission of signals to the IC tag frombeing interrupted by the water-containing content.

The above IC tags have been placed in the market, usually, in the formof an IC tag web in which a multiplicity of IC units comprising an ICchip and a metal antenna are fixed to the first thermoplastic resinsubstrate (usually, polyethylene terephthalate) sheet with an adhesiveor the like. The attaching method of the invention makes use of the ICtag web, fixes the second thermoplastic resin (usually, polyolefine suchas polypropylene) substrate sheet for heat-sealing onto the IC tag webto prepare a laminated sheet, successively punches the multiplicity ofIC units fixed onto the laminated sheet, fits the punched IC tag piecesonto the top plates of the caps successively simultaneously with thepunching, and fixes them by heat-melt-adhesion. According to thismethod, the IC tags which are light in weight and are of the shape ofsmall pieces are not treated by themselves but are treated in the formof the web or the laminated sheet in the process until they are fittedonto the top plates of the caps, avoiding such an inconvenience that theIC tags may fly off.

When the tag piece (IC tag) is fitted onto the top plate of the cap,too, the tag piece is readily false-fixed and is, thereafter,heat-melt-adhered to the top plate of the cap, effectively avoiding suchan inconvenience that the IC tag is removed from the top plate of thecap or is deviated in position before the IC tag is heat-melt-adhered tothe top plate of the cap integrally together.

As described above, the present invention makes it easy to handle the ICtags which are light in weight and are in the form of small pieces, andto effectively attach the IC tags to the top plates of the caps withoutcausing the IC tags to fly off or to be deviated in position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 include a side sectional view (a) and a plan view (b) showing thestructure of an IC tag to be attached to a cap according to theinvention.

FIG. 2 is a half-sectional side view showing an example of the cap inwhich a recessed portion having a bottom working as a shielding memberis formed in a top plate and the IC tag of FIG. 1 is attached to the topplate, together with a mouth portion of a container.

FIG. 3 is a half-sectional side view showing another example of theplastic cap of the invention having the IC tag attached to the top plateforming the recessed portion, together with the mouth portion of thecontainer.

FIG. 4 is a view showing half in cross section an embodiment of theplastic cap of the invention having the IC tag attached to the top plateforming the recessed portion, and in which an inner ring is providedseparately from a side wall of the recessed portion.

FIG. 5 is a half-sectional side view showing a preferred example of theplastic cap of the invention having the inner ring formed in a mannerdifferent from that of FIG. 4.

FIG. 6 is a view showing half in cross section the side surface of theplastic cap of FIG. 5 together with the mouth portion of the container.

FIG. 7 is a partially enlarged view showing, on an enlarged scale, theinner ring which is a major portion of the plastic cap of FIG. 5.

FIG. 8 is a half-sectional side view showing an example of the cap ofthe invention in which a shielding member is attached to the top platetogether with the mouth portion of the container.

FIG. 9 is a view schematically showing a process until the IC tag isattached to the cap.

FIG. 10 is a plan view illustrating a state of heat-adhering a laminatedsheet formed in the step of heat-laminating the IC tag of FIG. 9.

FIG. 11 is a view showing a step of fitting the IC tag of FIG. 9 ontothe cap.

FIG. 12 is a view illustrating a step of false-fixing the IC tag of FIG.9 onto the cap.

FIG. 13 is a view illustrating a step of heat-melt-adhesion in FIG. 9.

BEST MODE FOR CARRYING OUT THE INVENTION <Structure of the IC Tag>

Referring to FIG. 1( a) and FIG. 1( b), an IC tag (generally designatedat 10) has a structure in which a metallic antenna 3 and an IC chip 5are fixed onto an upper surface of a disk-shaped film 1 comprising afirst thermoplastic resin. Here, in order to attach the above IC tag 10to a cap, a film comprising a second thermoplastic resin is heat-adheredonto the back surface of the first thermoplastic resin film 1.

The first thermoplastic resin has a suitable degree of heat resistance,resistance against chemicals and strength to avoid deterioration at thetime of being heated for forming the metallic antenna 3 of apredetermined shape thereon, at the time of etching or at the time ofbeing pressed and heated for fixing the IC chip 5. Generally, the firstthermoplastic resin is a polyester resin such as polyethyleneterephthalate (PET). The film 1 comprising the above first thermoplasticresin has a thickness of, usually, about 7 to about 100 μm.

The metallic antenna 3, usually, comprises a thin film (having athickness of about 5 to about 50 μm) of a low-resistance metal, such asaluminum, copper, silver or gold, has a predetermined pattern, and isused for transmitting and receiving signals. The metallic antenna 3 isformed, usually, by sticking a metal foil onto the surface of the firstthermoplastic resin film 1 by heat-adhesion or, as required, by adhesionby using a suitable adhesive, and in a predetermined shape by etching.As the adhesive to be used as required, there is, usually, used anacid-modified olefin resin obtained by graft-modifying a polyolefinresin with an unsaturated carboxylic acid or a derivative thereof (e.g.,acid anhydride), or a thermosetting adhesive resin of the type of, forexample, urethane, isocyanate or epoxy.

The IC chip 5 is provided by, for example, flip-chip mounting so as tobe electrically conductive to the antenna 3, and stores informationrelated to a cap to which the IC tag 10 is attached or related to acontent and the like of a container to which the cap is attached.Namely, predetermined information is stored by transmitting signalsthrough the antenna 3, or information stored in the IC tag 10 is readout through the antenna 3.

As shown in FIG. 1( a), further, the IC chip 5 is, usually, sealed andprotected by using a sealing agent 7 such as polyimide or bismaleimideresin.

The second thermoplastic resin film 6 is used for firmly adhering andfixing the IC tag 10 to the top plate of the cap that will be describedlater by heat-melt-adhesion. As the second thermoplastic resin,therefore, there is used a resin material that can be favorablyheat-adhered to the polyolefin such as polypropylene or polyethyleneforming the cap or, concretely, there can be used the same resin as thecap resin material, such as polypropylene or polyethylene.

In the step of attaching the IC tag to the cap that will be describedlater, the second thermoplastic resin film 6 and the first thermoplasticresin film 1 are punched in a state of being laminated one upon theother. Therefore, the end surfaces of these films are forming acontinuous flat surface, and the IC tag 10 can be fixed byheat-melt-adhering an outer circumferential end surface 6 a of thesecond thermoplastic resin film 6 onto the top plate of the cap.

The second thermoplastic resin film 6 may have a thickness enough forbeing heat-adhered by heat-melt-adhesion and, usually, may have athickness of about 300 to about 1000 μm. In particular, since theheat-melt-adhesion is accomplished at the outer circumferential endsurface 6 a, it is desired that the thickness is better relatively largewithin the above range.

When the film 1 comprising the first thermoplastic resin such as PET isdirectly heat-melt-adhered to the top plate of the cap without suing theabove second thermoplastic resin film 6, the heat-adhesiveness is sopoor between the first thermoplastic resin and the cap material that theIC tag 10 cannot be firmly fixed to the top plate of the cap, permittingthe IC tag to be easily removed. Therefore, the IC tag 10 cannot oftenbe effectively utilized.

<Structure of the Cap>

Referring to FIG. 2 showing the cap to which the IC tag 10 is attached,the cap generally designated at 20 is, usually, made from a polyolefinsuch as polyethylene or polypropylene, and includes a top plate 21 and askirt wall 23 hanging down from the circumferential edge portion of thetop plate 21.

A screw 25 is formed in the inner surface of the skirt wall 23 to engagewith a screw 71 formed on the outer surface of a mouth portion 70 of acontainer to which the cap 20 is to be fitted. A tamper-evidence (TE)band 29 is provided at a lower end of the skirt wall 23 via a breakablebridge 27, and upwardly oriented flap pieces 30 are formed on the innersurface of the TE band 29 discretely along the circumference thereof.

That is, the cap 20 is fitted to the mouth portion 70 of the containerwith its screw 25 being screw-engaged therewith. Upon turning in thedirection of opening, the cap 20 fitted to the mouth portion 70 of thecontainer is removed from the mouth portion 70 of the container. At thetime of opening, the flap pieces 30 formed on the inner surface of theTE band 29 come into engagement with a flange portion 73 formed on theouter surface of the mouth portion 70 of the container limiting the TEband 29 from being lifted up. The bridge 27, therefore, breaks and theTE band 29 is separated away from the skirt wall 23. From the fact thatthe TE band 29 has been cut away, a general customer can recognize thatthe cap 20 was once removed from the mouth portion 70 of the container.

In the example of FIG. 2, first stopper pieces 31 are formed on thelower end surface of the skirt wall 23 maintaining a suitable gap, whilesecond stopper pieces 33 are formed on the upper end surface of the TEband 29 maintaining a suitable gap so as to be positioned among thefirst stopper pieces 31.

That is, the first stopper piece 31 has a side surface upright in thedirection of closing. In fitting the cap 20 to the mouth portion 70 ofthe container, the upright side surface of the first stopper piece 31comes in contact with the upright surface of the second stopper piece 33formed on the upper surface of the TE band 29, whereby the skirt wall 23and the TE band turn integrally together in the direction of closing,effectively avoiding the breakage of the bridge 27 at the time ofclosing.

The upper end surface of the second stopper piece 33 is a flat surface.At the time of closing, this surface comes in contact with the lower endsurface of the skirt wall 23, and a predetermined gap is maintainedbetween the upper end surface of the TE band 29 and the lower endsurface of the skirt wall 23, effectively preventing the breakage of thebridge 27 at the time of closing.

The invention, however, is not limited to the cap forming the abovestopper pieces 31, 33 only, but can be applied to the caps withoutforming such stoppers, too, as a matter of course.

The top plate 21, on the other hand, includes an annular flange 35 and arecessed portion 37 continuous to the inner circumferential edge of theannular flange 35.

On the inside of the outer circumferential edge portion on the uppersurface of the top plate 21, there are formed an annular flange 35 and arecessed portion 37 continuous to the inner circumferential edge of theannular flange 35. An upright stepped surface 40 is annularly formed ata boundary portion between the outer circumferential edge portion andthe annular flange 35.

The recessed portion 37 is formed by a side wall 37 a continuous to theinner circumferential edge of the annular flange 35 and a bottom 37 bclosing the lower end of the side wall 37 a. As shown, the outer surfaceside of the side wall 37 a is swelling outward to some extent. On theother hand, an outer ring 39 is formed on the inner surface of theannular flange 35, and an annular small protuberance 50 is formedbetween the outer ring 39 and a root portion of the side wall 37 a.

That is, when the cap 20 is fitted to the mouth portion 70 of thecontainer relying on the above screw-engagement, the inner surface of anupper part of the mouth portion 70 of the container comes into closecontact with the outer surface of the side wall 37 a, the outer side ofthe upper end portion of the mouth portion 70 of the container comes inclose contact with the inner surface of the outer ring 39, and the upperend surface of the mouth portion 70 of the container comes into closecontact with the small protuberance 50 to maintain favorable sealing.

In the present invention, the IC tag 10 is inserted in the inside of theouter circumferential edge portion of the upper surface of the top plate21 (i.e., in the portion on the inside of the stepped surface 40 andwhere the annular flange 35 and the recessed portion 37 are formed) in amanner that the IC chip 5 is on the lower side, and the circumferentialedge portion of the IC tag 10 (outer circumferential end surface 6 a ofthe second thermoplastic resin film 6) is heat-melt-adhered onto theannular stepped surface 40 on the outer circumferential edge portion ofthe annular flange 35. Therefore, the IC tag 10 is firmly fixed to thetop plate 21, and the recessed portion 37 is covered with the IC tag 10.

That is, in the present invention, the bottom 37 b of the recessedportion 37 formed in the top plate 21 works as a shielding memberreliably preventing the IC tag 10 from coming into direct contact withthe content (e.g., beverage) containing water in the container and,besides, maintaining a predetermined gap d between the signaltransmission surface (portion where the antenna 3 is formed) of the ICtag 10 and the bottom 37 b of the recessed portion 37 and, therefore,effectively preventing the transmission of signals from beinginterrupted by water contained in the content in the container. Thismakes it possible to reliably transmit signals to the IC tag 10 (IC chip5) or to reliably receive signals from the IC tag 10 in a state wherethe cap 20 is fitted to the mouth portion 70 of the container and,hence, to effectively input or output the product information.

In the invention, the size of the recessed portion 37 may be such thatthe transmission of signals to the IC tag 10 is not interrupted by waterin a state where water is in contact with the bottom 37 b of therecessed portion 37. Usually, the recessed portion 37 should have adepth (above-mentioned distance d) of not smaller than 7 mm though itmay differ depending, for example, upon the frequency of signals and thepattern of the antenna 3.

In the invention as shown in FIG. 3, further, a protuberance 60 forholding the IC tag 10 may be formed on the upper surface of the bottom37 b of the recessed portion 37.

That is, as will be understood from FIG. 3, the protuberance 60 ispositioned on the upper surface at the central portion of the bottom 37b, and a portion 7 of the IC tag 10 on where the IC chip 5 is providedis placed on the upper end of the protuberance 60. Upon providing theprotuberance 60 to support the IC tag 10, the IC tag 10 is effectivelyprevented from being deformed or broken in case an external force isexerted from the upper side of the cap 20. Further, to discard the cap20 after the use, the bottom 37 b of the recessed portion 37 is pushedupward from the side of the back surface. Namely, the IC tag 10 ispushed by the protuberance 60 and can be easily removed from the topplate 21 of the cap 20 offering advantage from the standpoint ofclassified disposal.

The above protuberance 60 does not necessarily have to be in contactwith, for example, the portion 7 on where the IC chip 5 of the IC tag 10is provided, and a slight degree of gap may be formed, for example,between the portion 7 and the upper end of the protuberance 60. Ineffect, the protuberance 60 may be so provided that the IC tag 10 is notgreatly deformed when the external force is exerted from the upperdirection. Therefore, the protuberance 60 is not limited to anembodiment of being provided at the central portion of the bottom 37 b.For instance, a plurality of protuberances 60 may be annularly arrangedsymmetrically about the center of the bottom 37 b in a manner that theprotuberances 60 support the portion where there is provided the antenna3 of the IC tag 10.

In the invention, it is desired that the IC tag 10 has the end surface 6a of the second thermoplastic resin film 6 attached byheat-melt-adhesion to the stepped surface 40 of the top plate 21.Depending upon the cases, further, the end surface 6 a of the secondthermoplastic resin film 6 may be mechanically fixed by insertion or thelike to the upper surface of the annular flange 35. Further,protuberances may be provided on the outer circumferential portions ofthe annular flange 35, and the protuberances may be folded in a statewhere the IC tag 10 is placed on the upper surface of the annular flange35 to thereby fix the circumferential edge portions of the IC tag 10.When the IC tag 10 is thus provided, the substrate 1 of the IC tag 10does not necessarily have to be formed by using a heat-melting materialsuch as a thermoplastic resin but may be formed by using a dielectricmaterial such as glass or the like. The IC tag 10 can be, further, fixedto the upper surface of the annular flange 35 by insertion.

According to the above embodiment, the upper part of the mouth portion70 of the container is inserted in space between the side wall 37 a ofrecessed portion of the top plate 21 and the skirt wall 23 to therebyfix the cap 20 to the mouth portion 70 of the container and to maintainsealing performance relying upon the close contact between the innersurface of the mouth portion 70 of the container and the side wall 37 aof the recessed portion. It is, however, also allowable to provide aninner ring as a member which is separate and independent from the sidewall 37 a of the recessed portion, and maintain sealing performance byusing the inner ring.

Namely, with the structure in which the upper part of the mouth portion70 of the container is inserted in space between the side wall 37 a ofthe recessed portion and the skirt wall 23 or in which the outer surfaceof the side wall 37 a is brought into close contact with the innersurface of the mouth portion 70 of the container to impart sealingperformance, the bottom 37 b that works as the shielding member iscontinuous to the lower end of the side wall 37 a integrally therewithand, therefore, the side wall 37 a has a low degree of flexibility.Therefore, the mouth portion 70 of the container may become difficult tobe inserted. Further, a close contact may not be attained between theside wall 37 a and the mouth portion 70 of the container, and sealingperformance may lose stability. On the other hand, the inner ring thatis provided quite separately from the side wall 37 a of the recessedportion is not affected by the bottom 37 b and maintains a high degreeof flexibility, making it possible to effectively prevent the aboveproblems.

FIG. 4 to FIG. 7 show caps provided with the above inner ring.

The caps 20 shown in FIG. 4 to FIG. 7 have basically the same structureas that of the cap 20 shown in FIG. 2 with the exception of theprovision of the inner rings and, therefore, the same reference numeralsare used for them, but the same members are not described here again.

Referring to FIG. 4, the cap 20 is provided with an inner ring 63 on theinner surface (lower surface) of the annular flange 35 of the top plate21. That is, the inner ring 63 is positioned between the skirt wall 23and the side wall 37 a of the recessed portion, and extends downwardmaintaining a gap relative to the skirt wall 23 and so will not to comein contact with the outer surface of the side wall 37 a of the recessedportion. Further, the inner ring 63 has an outer surface that isswelling outward at the central portion thereof, and comes intofavorable and close contact with the inner surface of the mouth portion70 of the container.

As will be understood from FIG. 4, the upper part of the mouth portion70 of the container is inserted in space between the inner ring 63 andthe skirt wall 23, whereby the outer surface of the inner ring 63 comesinto close contact with the inner surface of the mouth portion 70 of thecontainer to maintain favorable sealing performance. That is, unlike theside wall 37 a of the recessed portion, the lower end of the inner ring63 is not locked and, therefore, exhibits a high degree of flexibility.As a result, the mouth portion 70 of the container can be easily andsmoothly inserted and, besides, the outer surface of the inner ring 63comes into reliable and close contact with the inner surface of themouth portion 70 of the container making it possible to stably maintainexcellent sealing performance.

In the above embodiment, the inner ring 63 was provided on the innersurface of the annular flange 35. Referring to FIG. 5 which is ahalf-sectional side view, FIG. 6 which is a half-sectional side viewthereof together with the mouth portion of the container and FIG. 7which is an enlarged view showing a major portion, the cap 20 isprovided with an inner ring 63 at an intermediate portion of the sidewall 37 a of the recessed portion.

That is, in the cap shown in FIG. 5 to FIG. 7, a horizontal step 65 isprovided at the intermediate portion of side wall 37 a of recessedportion of the top plate 21, and the side wall 37 a includes an upperlarge-diameter portion A positioned on the upper side and having arelatively large outer diameter and a lower small-diameter portion Bpositioned on the lower side and having a relatively small outerdiameter (see FIG. 7). The inner ring 63 is formed on the outercircumferential surface of the upper large-diameter portion A, and isextending downward so will not to come in contact with the lowersmall-diameter portion B.

In the cap 20 provided with the above inner ring 63, too, like in thecap of FIG. 4, the upper part of the mouth portion 70 of the containeris inserted in space between the inner ring 63 and the skirt wall 23,and the lower end of the inner ring 63 (portion lower than the outwardlyswollen portion) is not locked, featuring a high degree of flexibility.Therefore, the mouth portion 70 of the container can be easily andsmoothly inserted enabling the outer surface of the inner ring 63 tocome into reliable and close contact with the inner surface of the mouthportion 70 of the container and, therefore, maintaining excellent andstable sealing performance.

In the embodiment of FIG. 5 to FIG. 7, further, the horizontal step 65is provided in the intermediate portion of side wall 37 a of therecessed portion to divide the side wall 37 a into the upperlarge-diameter portion A and the lower small-diameter portion B. Thehorizontal step 65, however, does not necessarily have to be provided ifthe inner ring 63 is not locked upon coming in contact with the outersurface of the side wall 37 a. The horizontal step 65 does not have tobe formed if, for example, the side wall 37 a of the recessed portion isso formed that its upper portion has a large diameter and its lowerportion has a small diameter and if the inner ring 63 so extendsdownward as will not to come in contact with the lower small-diameterportion.

Among the caps of the embodiments provided with the inner ring 63 asdescribed above, the cap 20 of the embodiment shown in FIG. 5 to FIG. 7is most desired. That is, in the embodiment of FIG. 5 to FIG. 7, theinner ring 63 is extending from the intermediate portion of side wall 37a of the recessed portion. Therefore, even if the water-containingcontent in the container may infiltrate into space between the innerring 63 and the side wall 37 a of the recessed portion, a predeterminedgap is maintained between the content in the container and thecircumferential edge portion of the IC tag 10 attached to the uppersurface of the annular flange 35 covering the recessed portion 37.Therefore, the transmission of signals is more reliably prevented frombeing interrupted by the content in the container.

In the above-mentioned embodiment, further, the recessed portion 37 isformed in the top plate 21, the bottom 37 b of the recessed portion 37works as the shielding member, and the predetermined clearance d ismaintained between the IC tag 10 attached to the top plate 21 and thewater-containing content in the container. Here, in the presentinvention, the above-mentioned clearance d may also be maintained byattaching a shielding member to the top plate 21.

For example, a cap of FIG. 8 is forming no recessed portion 37 that hasa bottom 37 b to work as the shielding member. Therefore, the top plate21 is substantially flat. At its central portion, however, there isformed a small recessed portion 21 a for receiving a portion 7 on whichthe IC chip 5 of the IC tag 10 is provided. An upright annular steppedsurface 40 is formed in the circumferential edge portion of the topplate 21 like in the cap of FIG. 1 to FIG. 7, and the IC tag 10 isfitted onto the top plate 21 with the side on where the IC chip 5 isprovided as the lower side, and is fixed by heat-melt-adhering the endsurface 6 a of the second thermoplastic resin film 6 onto the annularstepped surface 40.

Stopper pieces 31, 33 are omitted in the cap 20 shown in FIG. 8.

In FIG. 8, an inner ring 63 is provided on the lower surface of the topplate 21 so as to extend downward maintaining a gap relative to theskirt wall 23 and swelling on the outer surface side thereof. When thecap 20 is fitted to the mouth portion 70 of the container byscrew-engagement as described above, the upper part of the mouth portion70 of the container is inserted in space between the inner ring 63 andthe skirt wall 23, whereby the inner surface of the mouth portion 70 ofthe container comes into close contact with the outer surface of theinner ring 63 to maintain favorable sealing performance.

In the cap 20 of this embodiment, a shielding member 67 is attached tothe lower surface of the top plate 21 at a portion surrounded by theinner ring 63. The shielding member 67 has the same shape as the aboverecessed portion 37, and includes an annular side wall 67 a and a bottomwall portion 67 b. The bottom wall portion 67 b maintains a gap dbetween the antenna 3 of the IC tag 10 and the liquid level of thecontent in the container to a degree large enough for preventing thetransmission and reception of signals from being interrupted. It is,therefore, made possible to reliably transmit (input) productinformation to the IC tag and receive (output) product information thatis input without interrupting the transmission of signals(electromagnetic waves) due to dielectric loss and mismatching ofimpedance caused by water contained in the content in the container.

The shielding member 67 is made from the same resin (e.g., polyolefinresin) as the cap member. A thin flange portion 67 c extends outwardfrom the upper end of the annular side wall 67 a and is firmly fixed byheat-melt adhesion to the inner side of the inner ring 63 on the lowersurface of the top plate 21, preventing the content in the containerfrom leaking into the interior of the shielding member 67 and, further,preventing the sterilizing water used at the time of aseptic fillingfrom entering into the lower surface side of the top plate 21. Thus, thetransmission of signals is reliably prevented from being interrupted bywater. The shielding member 67 can be inserted in the inner surface sideat the root portion of the inner ring 63 without effecting the heat-meltadhesion. In this case, however, the shielding member 67 losesstability, and the effect for shutting off water becomes insufficient.When the aseptic filling is conducted, therefore, the sterilizing watermay infiltrate, and the transmission and reception of signals to andfrom the IC tag 10 lose stability. It is, therefore, desired that theshielding member 67 is provided by heat-melt adhesion.

As shown in FIG. 8, further, it is desired that the shielding member 67is of a shape that can be heat-melt-adhered near the root portion of theinner ring 63 so as to shut off a majority proportion of the antenna 3formed on the IC tag 10 from the content in the container. Further, theshielding member 67 can be heat-melt-adhered to the lower end of theinner ring 63. In this case, however, it becomes difficult to attainpress-adhesion at the time of heat-melt adhesion. As shown in FIG. 8,therefore, it is desired that the shielding member 67 isheat-melt-adhered near the root portion of the inner ring 63.

Thus, by using the shielding member 67 as a member separate from the topplate 21 and by attaching it to the lower surface of the top plate 21,it is allowed to maintain a predetermined gap d between the IC tag 10and the content containing water in the container. This embodiment,however, requires a step of heat-melt-adhering the shielding member 67in the step of forming a cap decreasing the productivity. As shown inthe embodiments of FIG. 2 to FIG. 7, therefore, a predetermined gap d isdesirably maintained by forming the recessed portion 37 in the top plate21.

<Attaching the IC Tag>

According to the present invention, the cap 20 is molded byinjection-molding various kinds of plastics followed by compressionmolding. Thereafter, the IC tag 10 is attached by means described below.

Referring to FIG. 9 illustrating the steps of the method of attaching ICtags of the invention, there are, first, provided an IC tag web 100 anda thermoplastic resin substrate sheet 103 for heat sealing.

The IC tag web 100 has a plurality of IC units 102 of a combination ofthe IC chip 5 and the metallic antenna 3 arranged and fixed on onesurface of a substrate 101 comprising the first thermoplastic resin(hereinafter simply referred to as first substrate sheet), the firstsubstrate sheet 101 corresponding to the above-mentioned firstthermoplastic resin film 1. That is, the IC tags 10 to be attached tothe caps 20 are, usually, placed in the market in the form of the IC tagweb 100 wound into a roll 105. The IC unit 102 is punched from the ICtag 23 b 100 and is fixed as the IC tag 10 onto the cap 20.

Further, a thermoplastic resin substrate sheet for heat sealing(hereinafter simply referred to as second substrate sheet) 103corresponds to the second thermoplastic resin film 6 mentioned above.The second substrate sheet 103 has the same width as the width of the ICtag web 100 (width of the first substrate sheet 101).

In the invention, the second substrate sheet 103 is wound into a roll107. The second substrate sheet 103 wound into the roll 107 is fed,taken up by a take-up roll 110 via a plurality of guide rolls 109, andon the way thereof are arranged the heat-laminating step and thepunching/fitting step.

In the heat-laminating step, the first substrate sheet 100 and thesecond substrate sheet 103 are heat-adhered together to laminate the ICtag web 100 on the surface of the second substrate sheet 103 to therebyform a laminated sheet A.

That is, in this step, a heating roller 111 and a pressing roller 113are arranged facing each other for attaining heat adhesion. The IC tagweb 100 is delivered from the roller 105. The delivered web 100 isoverlapped on the second substrate sheet 103 via a plurality of guiderollers 109, which, in this state, are passed through between theheating roller 111 and the pressing roller 113 where they are heated bythe heating roller 111 while being pressed by the pressing roller 113.Thus, the first substrate sheet 101 (first thermoplastic resinsubstrate) and the second substrate sheet (second thermoplastic resinsubstrate) 103 are heat-adhered together to form a laminate A having theweb 100 laminated on the surface of the second substrate sheet 103. Thelaminate A is intermittently taken up by the take-up roller 110 via aplurality of guide rollers 109 (i.e., the second substrate sheet 103 istaken up in the form of the laminate A), and is introduced into thepunching/fitting step that will be described later.

In conducting the heat adhesion, the IC tag web 100 is overlapped on thesecond substrate sheet 103 maintaining such a positional relationshipthat the IC units 102 are on the lower side and that the back surface ofthe first substrate sheet 101 faces the second substrate sheet 103.Therefore, the laminated sheet A obtained through this step has the ICunits 102 that are exposed on the lower surface. Further, the heatadhesion is effected under such a condition that the heating roller 111and the pressing roller 113 are heated by the heating roller 111 at atemperature which is not lower than the melting point of the secondsubstrate sheet 103 (second thermoplastic resin).

In the above heat-laminating step, it is desired to effect the heatadhesion without pressing a portion where the IC chip 5 is formed in theIC unit 102 on the IC tag web 100. Concretely, a groove is formed in theheating roller 111, and the heat adhesion is conducted by passing the ICchips 5 through the groove. As shown in FIG. 10, the thus obtainedlaminate A is not pressed at the central white spot portions X where theIC chips 5 are provided; i.e., these portions are becomingnon-melt-adhered portions or weakly melt-adhered portions, and hatchedportions Y on both sides thereof are becoming melt-adhered portions. Byconducting the heat adhesion as described above, breakage of the ICchips 5 due to the pressing can be reliably avoided.

Reverting to FIG. 9, the laminate A of the IC tag web 100 and the secondsubstrate sheet 103 formed as described above, is intermittently takenup by the take-up roll 110, and is intermittently conveyed to thepunching/fitting step via a cooling roller 115 and a plurality of guiderolls 109.

In the punching/fitting step, a hollow guide 200 is positioned and fixedover the laminated sheet A, and a hollow punch 201 for punching isarranged over them so as to move up and down. Further, a pushing punch203 is arranged so as to move up and down passing through the inside ofthe hollow punch 201.

Further, a hollow die set 205 is positioned and fixed on the lower sideof the laminated sheet A, and a support table 207 that intermittentlyrotates is arranged on the lower side thereof. The caps 20 having theabove-mentioned structure are held on the support table 207 by suctionor the like, and are fed to a predetermined position on the lower sideof the die set 205 in synchronism with the laminated sheet A that isintermittently fed.

Referring to FIG. 9 as well as FIG. 11 which illustrates thepunching/fitting step, the cap 20 is covered with an adaptor 310 (seeFIG. 11( a)) prior to being introduced into the above step.

The adaptor 310 is for fitting a tag piece B punched from the laminatedsheet onto the upper surface of top plate of the cap 20 withoutpositional deviation, has an opening 311 permitting the upper surface oftop plate of the cap 20 to be exposed, and has a tapered surface 311 aformed at an upper end portion thereof being tilted downward and inward.The adaptor 310, further, has a notch 313 for conducting the falsefixing by spot melt adhesion that will be described later.

That is, the cap 20 covered with the adaptor 310 stops on the lower sideof the die set 205. In this state, the hollow punch 201 moves downpassing through the opening of the guide 200 to punch the tag piece B ina disk shape from the laminated sheet A. As shown in FIG. 9, the tagpiece B that is punched is of the structure in which the secondsubstrate 103 corresponding to the second thermoplastic resin substratefilm 6 is adhered to the IC tag 10 of FIG. 1, and has a diametersubstantially the same as the diameter of the stepped surface 40 of thecap 20.

The punched tag piece B is temporarily held on the upper side of theadaptor 310 by a pawl 205 a provided on the lower side of the die set205 (see FIG. 11( b)).

Next, in this state, the pushing punch 203 moves down passing throughthe opening of the die set 205 to push and fit the punched tag piece B(IC tag 10) to the top plate (inside of the stepped surface 40) of thecap 20 (see FIG. 11( c)). Thus, the tag piece B having the IC tag 10 isfitted so that the IC unit 102 provided in the tag piece B faces the capside, that the second substrate sheet 103 is on the outer surface side,and that the circumferential edge portion of the second substrate 103faces the annular flange 35 of top plate of the cap. That is, due to thetapered surface 311 a formed in the adaptor 310, the punched tag piece B(IC tag 10) is smoothly fitted to the above position without deviated inposition.

After the tag piece B is punched from the laminated sheet A and isfitted as described above, the pushing punch 203 and the hollow punch201 move up, the laminated sheet A from which the tag piece B with ICtag 10 is punched is taken up by the take-up roll 110, and the cap 20 towhich the tag piece B is fitted is intermittently fed in a state ofbeing covered with the adaptor 310 to the next false-fixing step due tothe intermittent turn of the support table 207.

According to the present invention as described above, the tag piece Bto which the IC tag 10 is fixed is punched from the laminated sheet Aand is fitted to the cap 20 simultaneously without passing through thestep of conveyance. Besides, the IC tags 10 which are small and light inweight are not handled by themselves but are handled in the form of along sheet from the above-mentioned heat-laminating step up to thepunching/fitting step reliably preventing the IC tags 10 from flyingoff.

In the above punching/fitting step, the tag piece B is fitted to theupper surface of top plate 21 of the cap 20, i.e., fitted to the insideof the annular stepped surface 40 and, therefore, is in a false-fixedstate. However, the above false-fixing only may not often be sufficient.In such a case, as shown in FIG. 11( c), an inwardly protruded undercut320 may be formed at an upper end (upper end of the stepped surface 40)on the inside of the circumferential edge of top plate 21 of the cap 20.When the above undercut 320 is formed, the tag piece B that is fitted isfirmly fixed upon being engaged with the undercut 320.

According to the present invention as described above, the tag piece Bcan be fitted and false-fixed simultaneously through thepunching/fitting step. Desirably, however, the false-fixing step isprovided after the punching/fitting step.

Referring to FIG. 9, the cap 20 to which the tag piece B is fitted isintroduced into the false-fixing step due to the intermittent turn ofthe support table 207, and the tag piece B (IC tag 10) is false-fixed byspot-melt adhesion.

Reference is made to FIG. 12 explaining the false-fixing step. In thefalse-fixing step provided separately from the punching/fitting step, asealing rod 351 having a slender rod-like false-melt-adhering head 350at an end thereof moves down from over the cap 20 that is supported onthe support table 207 and is covered with the adaptor 310. Thefalse-melt-adhering head 350 passes through the notch 313 formed in theadaptor 310 to come into pressed contact with the circumferential edgeportion of the tag piece B (i.e., circumferential edge portion of thesecond substrate 103 of IC tag 10) that is facing the annular flange 35of top plate 21 of the cap to heat the above portion. Therefore, thesecond substrate 103 is heat-melt-adhered to the top plate 21 (annularflange 35) of the cap as a spot, and the tag piece B or the IC tag 10 isfalse-fixed. The spot-melt adhesion can be attained in a very shortperiod of time (about 0.1 second) as compared to the whole-meltadhesion. Besides, the above false-fixing helps effectively avoid suchan inconvenience that the tag piece B is removed away from the cap 20before the tag piece B (IC tag 10) is completely fixed in the subsequentheat-melt-adhering step.

After the above false-fixing, the adaptor 310 moves up so as to beremoved from the cap 20 and is put again onto a cap of before thepunching/fitting step. Further, the cap 20 to which the tag piece B (ICtag 10) is false-fixed is intermittently fed by the intermittent turn ofthe support table 207, transferred from the support table 207 onto aconveyer belt 360 that is continuously driven, transmitted from theconveyer belt 360 onto a continuously turning table 363 via anintermediate table 361, and the tag piece B (IC tag 10) is finally fixedin the final heat-melt-adhering step while being continuously fed by thetable 363.

Reference is now made to FIG. 9 together with FIG. 13 which explains theheat-melt-adhering step. In this step, a heat-sealing member 370 movesin synchronism with the continuously turning table 363, and is arrangedalong the direction in which the continuously turning table 363 turns.

The heat-sealing member 370 has, at its lower end, a sealing head 371 ofa shape corresponding to the circumferential edge portion of the secondsubstrate 103 that is adhered and fixed to the tag piece B (IC tag 10).The heat-sealing member 370 moves down and comes into pressed contactwith the circumferential edge portion of the second substrate sheet 103of tag piece B false-fixed to the cap 20. In this state, theheat-sealing member 370 moves together with the cap 20 and isheat-melt-adhered by the sealing head 371; i.e., the outercircumferential end surface of the second substrate 103 of tag piece B(end surface 6 a of the film 6) that is false-fixed is pushed onto theannular stepped surface 40 and is heat-melt-adhered thereto so as to becompletely fixed. The sealing time in this case is about one second.

After the heat-melt adhesion is finally conducted as described above,the heat-sealing member 370 moves up so as to be removed from the cap20, and is melt-adhered again onto the next cap 20. Further, the cap 20to which the tag piece B (IC tag 10) is completely fixed is transferredonto a discharge table 375 that is continuously turning, continuouslydischarged from the table 375, and is collected as a final product.

Thus, there is obtained the cap with IC tag having the IC tag 10 shownin FIG. 1 that is fixed to the upper surface of top plate 21 of the cap.

In the foregoing was described the method of attaching the IC tag 10with reference to the case of the cap 20 of FIG. 2 having the recessedportion 37 formed in the top plate 21. It will, however, be obvious thatthe IC tag 10 can be similarly attached to the cap without forming therecessed portion 37 as well.

In the example of FIG. 9, further, while the second substrate sheet 103is being intermittently taken up by the take-up roller 110, provision ismade of the heat-laminating step and the punching/fitting step to effectthe heat-lamination and punching/fitting. Here, after heat-laminated,the laminate A may be once taken up and may be conveyed to another placeto effect the punching and fitting. In this case, since theheat-laminating step and the punching/fitting step are conductedcompletely independently from each other, there is obtained an advantagein that the IC tag web 100 and the second substrate sheet 103 arecontinuously conveyed and are continuously heat-laminated.

According to the method of attaching IC tags of the invention describedabove, the IC tags which are very light in weight and difficult tohandle can be efficiently attached to the top plates of the capsmaintaining high productivity without accompanied by such inconveniencesas flying off and deviation in position.

In attaching the IC tags 10, further, it is also allowable, for example,to punch the IC units 102 from the IC tag web 100, heat-laminate them onthe second substrate sheet 103 to form the laminate, convey the laminateto the punching/fitting step, and fit the IC tags 10 to the caps 20while punching the IC units 102 from the laminate. With this means,however, the IC units 102 must be punched twice requiring a very complexcontrol operation for intermittently feeding the IC tag web 100.According to the present invention, however, the IC units 102 arepunched only once in the punching/fitting step requiring an easy controloperation for intermittent feeding and featuring a very highproductivity.

1. A one-piece plastic cap to be fitted to a mouth of a container whichcontains a water-containing content, and having a top plate and a skirtwall hanging down from a circumferential edge portion of the top plateand, further, having an IC tag storing product information attached toan upper surface of said top plate, wherein: said top plate forms ashielding member that maintains a gap between the water-containingcontent in the container and said IC tag to such a degree that thetransmission and reception of signals to and from the IC tag are notinterrupted by the water-containing content.
 2. The one-piece plasticcap according to claim 1, wherein: said top plate is formed by anannular flange and a recessed portion continuous to an innercircumferential edge of the annular flange; said recessed portionincludes a side wall continuous to the inner circumferential edge ofsaid annular flange, and a bottom continuous to a lower end of said sidewall and the bottom is working as said shielding member; and said IC tagis attached to said annular flange to cover said recessed portion, andwherein a gap between said IC tag and the bottom of said recessedportion is maintained to such a degree that transmission and receptionof signals to and from said IC tag are not interrupted when a backsurface of said bottom comes in contact with the water-containingcontent.
 3. The one-piece plastic cap according to claim 1, wherein saidIC tag is attached by heat-melt-adhering the circumferential edgeportion thereof onto the upper surface of said top plate.
 4. Theone-piece plastic cap according to claim 2, wherein a protuberanceextending upward is formed on an upper surface of the bottom of saidrecessed portion.
 5. The one-piece plastic cap according to claim 2,wherein the side wall of the recessed portion of said top plate includesan upper large-diameter portion having a relatively large outer diameterand a lower small-diameter portion having a relatively small outerdiameter, an inner ring is formed on the outer circumferential surfaceof the upper large-diameter portion of said side wall so as to extenddownward being separated away from the outer circumferential surface ofthe lower small-diameter portion, and the mouth of the container isinserted in space between said skirt wall and the inner ring so as to befixed therein.
 6. A method of attaching an IC tag to a plastic cap,comprising steps of: preparing an IC tag web in which a plurality of ICunits of a combination of IC chips and metal antennas are arranged andfixed on one surface of a first thermoplastic resin substrate sheet, asecond thermoplastic resin substrate sheet, and a plastic cap having atop plate and a skirt wall hanging down from a circumferential edgeportion of the top plate; preparing a laminated sheet in which said ICtag web is laminated on a surface of the second thermoplastic resinsubstrate sheet by heat-adhering the first thermoplastic resin substratesheet of said IC tag web and the second thermoplastic resin substratesheet together in a manner that said IC units are positioned on an outersurface side; punching said laminated sheet in a disk shape successivelyfor each of the IC units fixed thereto to thereby successively form tagpieces of the disk shape having the second thermoplastic resin substrateadhered to the IC tag in which one IC unit is fixed to the firstthermoplastic resin substrate, and successively fitting and false-fixingthe punched tag pieces onto the upper surfaces of the top plates of thecaps in a manner that the second thermoplastic resin substrate is on theouter surface side simultaneously with the punching; and fixing said ICtag onto the top plate of the cap via the second thermoplastic resinsubstrate in an integral form by heat-melt-adhering the secondthermoplastic resin substrate onto the upper surface of the top plate ofthe cap.
 7. The method according to claim 6, wherein the firstthermoplastic resin substrate sheet comprises polyethylene terephthalateand the second thermoplastic resin substrate sheet comprises polyolefin.8. The method according to claim 6, wherein a stepped surface is formedin an annular shape at the outer circumferential edge portion on theupper surface of the top plate of said cap, the inner region of saidstepped surface forms a surface lower than the outer region, and the tagpiece punched from the laminated sheet is fitted onto the inner regionof said stepped surface.
 9. The method according to claim 8, wherein thetag piece punched from the laminated sheet is inserted into an innerportion of said stepped surface in a manner that the outercircumferential end surface of the second thermoplastic resin substrateis closely adhered to said stepped surface, and is, thus, fitted onto,or is fitted and false-fixed onto the upper surface of the top plate ofthe cap.
 10. The method according to claim 8, wherein an undercut isformed in an upper end portion of said stepped surface so as to protrudeinward, and the tag piece is false-fixed by an engagement of saidundercut with an outer circumferential edge portion of the secondthermoplastic resin substrate.
 11. The method according to claim 8,wherein the inner region of the stepped surface on the upper surface ofthe top plate of said cap includes an annular flange continuous to thelower end of said stepped surface and is extending inward, and arecessed portion continuous to the inner circumferential edge of saidannular flange, and said tag piece is so fitted that the circumferentialedge portion thereof faces said annular flange.
 12. The method accordingto claim 6, wherein the first thermoplastic resin substrate sheet andthe second thermoplastic resin substrate sheet are heat-adhered togetherin a manner that at least the IC chip is not pressed on the surface ofthe first thermoplastic resin substrate sheet.
 13. The method accordingto claim 6, wherein said IC tag web is laminated while intermittentlyfeeding said second thermoplastic resin substrate sheet, the laminatedsheet is punched after having been laminated, and the punched tag piecesare fitted onto the top plates of the caps.
 14. The method according toclaim 6, wherein the second thermoplastic resin substrates possessed bysaid IC tag pieces are spot-heat-adhered onto the upper surfaces of thetop plates of the caps so that the tag pieces are false-fixed whileintermittently feeding the caps having the tag pieces fitted onto theupper surfaces of the top plates thereof.
 15. The method according toclaim 6, wherein the caps to which the tag pieces are false-fixed areintroduced into the step of continuous feeding, and the secondthermoplastic resin substrates possessed by the tag pieces areheat-melt-adhered onto the upper surfaces of the top plates of the capswhile continuously feeding said caps so that said IC tags are fixed tothe top plates of said caps integrally therewith.